Conventionally, a large amount of heat energy is released and lost as, for example, waste heat, light, etc. in various energy-using devices such as internal combustion engines including an automobile engine; heat exchangers including a boiler and air-conditioning equipment; motor generators including a power generator and a motor; and luminous devices including lightings.
Nowadays, recovery and recycling of released heat energy as an energy source has been required in view of energy conservation, and as such a method, for example, Non-Patent Document 1 below has proposed a thermoelectric generator (TEG), in which an exhaust gas heat exchanger is provided between an exhaust gas purifying catalyst and a muffler in an exhaust gas system of automobiles, and in the exhaust gas heat exchanger, the exhaust gas in the exhaust pipe is homogenized, and a thermoelectric element (thermoelectric module) composed of Bi2Te3 is disposed between the exhaust pipe and a radiator.
In the thermoelectric generator, the thermoelectric element is disposed between the exhaust pipe warmed by the exhaust gas, and the radiator, and a temperature difference is caused at one side and the other side thereof to generate electricity by the Seebeck effect of the thermoelectric element. The thus obtained electric power is usually stored in onboard batteries via a step-up DC-DC converter, and used suitably as necessary.